Previously, in order to hold an external pressure transducer in place to effectively monitor the uterine contractions of a pregnant patient, it was necessary to use a flexible belt wrapped around the body of the patient. This is commonly referred to as a tocodynamometer or toco belt. Such a toco belt is easy to apply, but not easy to use, and further, it is not possible for the toco belt to maintain the transducer in a stable position. Movement of the patient, even such mild movement as the patient rolling over in bed, will result in the loss of reliability of the signal of the transducer. Walking or exercising is not possible at all without loss of the signal.
The applicant has used an adhesively applied transducer support base that permits the transducer to be fixed directly to the patient so that reliable data can be obtained, even with vigorous movement by the patient, such as during walking and exercising.
In copending application Ser. No. 915,130 the use of a substantially concave support base having a central hollow tubular member was disclosed. The support base was adhesively attached to the patient and the transducer fitted into the hollow tubular member and was held against the abdomen by pressure applied by a cap.
Such a device was found to work reliably, but had limited value on very obese patients. With obese patients, this device required a special support plate that had a hollow tubular member that could be adjusted so as to press downwardly into the abdomen of the heavy patient, so that the transducer could obtain reliable measurements of the contractions. However, the pressure of the extended hollow tubular member against the abdomen was uncomfortable, particularly if the device was used for a substantial length of time.
In copending patent application Ser. No. 118,441 a series of struts was devised connecting the hollow tubular member to a flexible support plate. This modification permits one basic support plate to be used on different sized patients. The struts serve to effectively lower the central portion of the hollow tubular member in relationship to the perimeter of the flexible support plate, thereby causing the perimeter of the hard area of the support plate to form, in effect, an isolation ring which caused increased tension in the confined cutaneous tissue. Such a device, however, is not as simple to use as a device with no adjustable parts, and also is more expensive to manufacture.